Cannot resolve plugin org.mortbay.jetty:maven-jetty-plugin:6.1.7

This error usually occurs when Maven is unable to download the required plugin from the remote repository.

To resolve this issue, you can try the following steps:

1. Check if you have an active internet connection.
2. Try running the Maven build again with the '-U' option to force an update of the local repository. For example, run 'mvn clean install -U'.
3. If the issue persists, try deleting the contents of the local repository located in the .m2 directory and run the build again.
4. If none of the above steps work, you can try adding the following repository to your pom.xml file:

   <repositories>
     <repository>
       <id>central</id>
       <url>https://repo.maven.apache.org/maven2</url>
     </repository>
   </repositories>

This will ensure that Maven downloads the required plugin from the central repository.

I hope this helps! Let me know if you have any further questions.